Indications:
Fexofenadine is an antihistamine with selective peripheral H-1 receptor antagonist activity. This agent is effective in the management of seasonal allergic rhinitis and chronic idiopathic urticaria. Other indication are sneezing,rhinoria,itchy nose,itchy/watery/red eyes.
Doses & Administrations:
NON - SEDATING ANTI HISTAMINE ----- Seasonal Allergic Rhinitis: dose is 120 mg QD. Chronic Idiopathic Urticaria: dose is 180 mg QD. Max dose = 480 mg/day Pediatric: 6-11 years : 30 mg BID (Qd for renal compromised patients) > 12 years : As for adults
Pharmacodynamics
Fexofenadine is a second-generation, long lasting H1-receptor antagonist (antihistamine) which has a selective and peripheral H1-antagonist action. Histamine is a chemical that causes many of the signs that are part of allergic reactions, such as the swelling of tissues. Histamine is released from histamine-storing cells (mast cells) and attaches to other cells that have receptors for histamine. The attachment of the histamine to the receptors causes the cell to be "activated," releasing other chemicals which produce the effects that we associate with allergy. Fexofenadine blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of cells by histamine. Unlike most other antihistamines, Fexofenadine does not enter the brain from the blood and, therefore, does not cause drowsiness. Fexofenadine lacks the cardiotoxic potential of terfenadine, since it does not block the potassium channel involved in repolarization of cardiac cells
Mechanism of action
Like other H1-blockers, Fexofenadine competes with free histamine for binding at H1-receptors in the GI tract, large blood vessels, and bronchial smooth muscle. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms (eg. nasal congestion, watery eyes) brought on by histamine. Fexofenadine exhibits no anticholinergic, antidopaminergic, alpha1-adrenergic or beta-adrenergic-receptor blocking effects.
Contra Indications:
Fexofenadine is contraindicated in pts. with known hypersensitivity to any of its ingerdients.
Pregnancy Status:
Category "C"
Renal Failure Doses:
Creatinine Clearance < 40 ml/min ........ 60 mg once daily
Lactation Status:
Unknown
Co-adminstration with macrolides or azole anti-fungals has been reported to increase fexofenadine maximal concentration at steady state and time to maximum concentration at steady state.
Adverse Effects:
The most common adverse effect are drowsiness, fatigue, nausea, dyspepsia. Rarely leukopenia is reported.
Overdosage
Dizziness, drowsiness, and dry mouth have been reported with Fexofenadine hydrochloride overdose. Single doses of Fexofenadine hydrochloride up to 800 mg (6 healthy subjects at this dose level), and doses up to 690 mg twice daily for 1 month (3 healthy subjects at this dose level) or 240 mg once daily for 1 year (234 healthy subjects at this dose level) were administered without the development of clinically significant adverse events as compared to placebo.
In the event of overdose, consider standard measures to remove any unabsorbed drug. Symptomatic and supportive treatment is recommended. Following administration of terfenadine, hemodialysis did not effectively remove Fexofenadine, the major active metabolite of terfenadine, from blood (up to 1.7% removed).
No deaths occurred at oral doses of Fexofenadine hydrochloride up to 5000 mg/kg in mice (110 times the maximum recommended daily oral dose in adults and children based on mg/m2) and up to 5000 mg/kg in rats (230 times the maximum recommended daily oral dose in adults and 210 times the maximum recommended daily oral dose in children based on mg/m2). Additionally, no clinical signs of toxicity or gross pathological findings were observed. In dogs, no evidence of toxicity was observed at oral doses up to 2000 mg/kg (300 times the maximum recommended daily oral dose in adults and 280 times the maximum recommended daily oral dose in children based on mg/m2).
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Fexofenadine Mechanism of action
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Ditulis oleh:
Unknown - Saturday, 30 July 2011
